Continuous pipe, generally known within the industry as coiled tubing since it is stored on a large reel, has been used for many years. It is much faster to run into and out of a well bore than conventional jointed straight pipe since there is no need to join or disconnect short segments of straight pipe.
Coiled tubing “injectors” are machines that are used to run continuous strings of pipe into and out of well bores. Examples of coiled tubing injectors include those shown and described in U.S. Pat. Nos. 5,309,900, 6,059,029 and 6,216,780. A crane, mast or rig is typically used to hold the injector and a blowout preventer on top of the wellhead while the injector is operated to run coiled tubing in and out of the well. A reel, on which the tubing is stored, and the injector are operated in conjunction so that tubing is unwound from the reel as the injector is inserting it into the well bore, and wound back on the reel as the injector is removed from the well bore.
Generally, it is undesirable to have electric devices at a well site because of the risk of igniting an explosion. Therefore, only hydraulic power is used to operate the reel and the injector. A “power pack” supplies pressurized hydraulic fluid to hydraulic motors on the reel and the injector. The power pack includes a diesel-powered engine turning a hydraulic pump. A operator controls the operation of the reel and injector by controlling the flow of hydraulic fluid to the motors using a set of valves. The hydraulic system controls are placed in a small cabin, in which an operator sits.
The reel and the injector must be operated synchronously to avoid placing excessive stress on the tubing and other problems. The coiled tubing must also be properly wound back on the reel. Therefore, the operator prefers to be in a position that allows him to view simultaneously the injector and the reel. This position is usually directly behind the reel, in line with the tubing and injector. Therefore, the operator's control cabin is placed behind the reel, generally in line with the reel and injector.
Because of the relatively large size of the reels, the cabin must be elevated to enable the operator to see over the reel. However, to transport the cabin to the well site it also must be small and compact. Cabins therefore typically include some sort of lifting mechanism that allows the cabin to be raised to an elevated position when set up at the well site.